She then leaves; romeo begins to go, juliet reappears a second time. it is apparent that neither one wants the night to end. juliet's parting line is probably the most famous exit line in literature. what is it?

These lines are:

Parting is such sweet sorrowThat I shall say good night till it be morrow.

Neither Romeo nor Juliet want this night to end because they don't want to leave each other's side. They want to stay together the entire night, but given that they are unable to, Juliet speaks those famous parting words, wishing to meet Romeo again in the morning.